Bulk storage tanks, such as above-ground fuel tanks or dry bulk storage tanks, typically include one or more access ports that permit filling the tank with bulk material (such as liquid fuel or dry bulk goods), and that permit removing or dispensing bulk materials from the tank. Typically, such tanks are not highly secured against unauthorized access or tampering, which makes them vulnerable to such access and theft. This can be particularly problematic when the bulk materials contained in the tanks are highly valuable, such as liquid fuels.